JPS628047A - Apparatus for outputting dew point temperature - Google Patents

Abstract

PURPOSE:To simplify the circuit of an operator while enhancing an operation speed and to make it possible to immediately output dew point temp., by calculating dew point temp. from relative humidity and dry bulb temp. according to a specific formula. CONSTITUTION:A humidity signal output part 1 outputs voltage represented by a primary function having relative humidity phi as a variable and a temp. signal output part 2 changes an amplifying degree on the basis of resistance represented by primary function having temp. as a variable. Further, a multiplier 3 inputs the output of the output part 1 and this input and output are bypassed through the output part 2. By this method, the multiplication of the temp. output signal and the relative humidity output signal is performed according to formula (wherein phi is relative humidity, t is dry bulb temp., td is dew point temp., and a, b and c are constant). Then, a dew point temp. value is outputted to an output part 4 as a voltage value.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a dew point temperature output device for calculating dew point temperature from dry bulb temperature and relative humidity.

Conventional technology Conventionally, dew point meters have been used to measure dew point temperature, but these dew point meters have a slow reaction rate and are expensive, so it is difficult to calculate dew point temperature from dry bulb temperature and relative humidity. It is considered. In this case, within the temperature and pressure range used in general air conditioning, the following (→, (→, (
I'm looking for it from the Ha-style.

td=Tcθd-273,16・・・・・・・・・・・・
・(→h(θd)=ψ・h(t)/100 ・
・・・・・・・・・・・・(→Here, t is the dry bulb temperature ['C
), ψ is the relative humidity [chi], h(:t) is the saturated vapor pressure (
-g), td is dew point temperature [''C], Tc is critical temperature ['C), Pc is critical pressure [Hq]
In order to find the dew point temperature td at t, the practical international equation of state (c), which is a calculation formula for saturated vapor pressure, is used, and therefore the calculation of the dew point temperature td is very complicated.

Problems to be Solved by the Invention However, in order to determine the dew point temperature of humid air using the conventional method, it had to be determined using a computer or the like, making it difficult to obtain a dew point temperature output device with a simple circuit configuration. .

Moreover, the calculations are complicated and require a long time to complete.

In view of the above-mentioned problems, the present invention provides a dew point temperature output device which can easily measure dew point temperature, has a simple configuration, and has a fast calculation speed.

Means for Solving the Problems In order to achieve the above object, the present invention provides a dry bulb temperature t (°C).
and the relative humidity ψ (%), find the dew point temperature td using the formula t d = a t tp + b t + cψ + d, and calculate the constants of a, b, c, and d as true under the specified temperature and humidity range. The configuration includes an arithmetic unit selected so that the dew point temperature tdo of the value and the dew point temperature td from the arithmetic expression become l td - tdo l<1°C.

Function: With the above configuration, calculations can be performed using simpler calculation formulas than in the past, so the configuration of the calculation unit can be simplified and the calculation speed can be increased.

Example The calculation formula for the dew point temperature td of the present invention is td = a tψ+bt +cψ+d
---(d) However, a, b, c, and d are constants, and td = C (t + p) (ψ + q) + τ
It can be expressed as ・・・・・・・・・(E).

According to the arithmetic expression (d) or (e) according to the present invention, dew point temperature calculation is performed without performing complicated calculations using the conventional equations (a), (b), and (c).

Next is the calculation formula (d)! Or, explain how to derive the equation (E).

Figure 6 shows the dew point when the relative humidity ψ is constant, based on the hygrodynamic diagram (1-X diagram) and the basic formulas (a), (b), and (c) for dew point temperature calculation. It is a relationship diagram in which temperature tdo value is plotted against dry bulb temperature t. In this case, the dew point temperature td can be approximated by a linear relationship diagram of the dry bulb temperature and can be expressed by the following equation.

td=mt+n ・Mountain...
・(to) Here, m and n are constants.

Next, when considering the correction of the coefficients m and n for each humidity, in a certain humidity range ψ1 to y, as shown in Figures 7 and 8, m and n are approximate expressions of the linear function of the relative humidity ψ, respectively. It can be expressed as ()) and (ch).

m= 6ψ+b...
Song Kento) n=C・ψ+d ... Song... (H) Here, a, b, c, and d are constants.

Therefore, by substituting equations (g) and (h) into equation (f), equations (2) and (e), which are the operational equations of the present invention, can be obtained.

In this case, as shown in Figure 6, the equation of the straight line ψ1 = 1oO%.

and the equation of the straight line with ψ4=70% are td = (
0,999996) t +1.98364X10-5
(When ψ1) td g (0,9608516) t -4,818
41 (at the time of ψ4). From the above formula, ψ1~啼. coefficients m, n in the range of
Figures 7 and 8 are graphs obtained by calculating each of them, and m = 1,30205X10 ψ + 0.870688, respectively.
n = 0.160164ψ-16,9073.

Therefore, in this case, the constants of a, b, c, and d are a
= 1, 30206X10-5 b = 0.870688 C = 0.160164 d = -1es, 9073. By substituting these constants a, b, c, and d into equation (d), Table 1 shows the difference between the dew point temperature found from the international equation of state that is close to the true value and the dew point temperature found from equation (d).

Table 1 As shown in Table 1, the dew point temperature t determined by equation (d)
d is highly accurate, with a difference of 0.3 or less from the dew point temperature tdo determined by the basic formulas (a), (b), and (c) over the entire range of relative humidity from 70 to 100 inches, and is also suitable for practical use. The accuracy is sufficiently high within the range of temperature and relative humidity.

In addition, by changing the relative humidity range and finding the coefficients of calculation formulas (d) and (e), we can calculate the electric signal expressed by the humidity function and the electric signal expressed by the linear function of relative humidity. Since it can be configured with a multiplier with a constant signal and an adder with a constant signal, it can be realized with a simple circuit configuration.

Next, an embodiment of a dew point temperature output device that performs the calculation expressed by the calculation formula (e) will be described with reference to FIGS. 1 to 6.

FIG. 1 is a basic configuration diagram of a dew point temperature output device of the present invention, in which a humidity signal output section 1 outputs a voltage expressed by a linear function with relative humidity ψ as a variable. Temperature signal output section 2
The degree of enhancement is changed by the resistance expressed by a linear function with temperature as a variable. Furthermore, the multiplier 3 inputs the humidity signal output section 1, and by bypassing this input section and the output section via the temperature signal output section 2, multiplies the temperature output signal and the relative humidity output signal to obtain the dew point. The configuration is such that the temperature value is output to the output section 4 as a voltage value.

A more specific example of the circuit is shown in FIG.

In FIG. 2, a humidity sensor 6 consisting of a resistor 6 and a resistor 9 that detect humidity changes as resistance changes are connected in series.
The voltage value output to terminal 7, which is this connection point, is the value obtained by dividing the voltage applied to terminal 8 by the ratio of humidity sensor 6 and resistor 9. This constitutes a linear function of relative humidity, and outputs a humidity signal. ing. 1o is an operational amplifier, and when a voltage expressed as a linear function of relative humidity is inputted to an inverting input terminal, a voltage is outputted to a terminal 14 according to the degree of increase determined by a composite resistance 13 of a resistor 11 and a thermistor 12. Here, the thermistor 12 is a temperature sensor,
A thermistor with a large B constant is used to configure the temperature signal output section 2 expressed by a linear function with temperature as a variable.

Output from terminal 14: ``The voltage is the product of a linear function with relative humidity as a variable and a linear function with temperature as a variable. The output section 4 is a constant addition section of the approximate calculation formula (e).

The operational amplifier 15 is used as an adder to add the voltage at the terminal 14 and the voltage at the terminal 1e. As a result, the dew point temperature expressed by the approximate calculation formula (e) is outputted to the terminal 17 as a voltage value.

FIG. 3 shows another embodiment of the present invention, in which A
section is a relative humidity signal output section, and when a capacitor 107 is connected to the non-inverting input side of the operational amplifier 106 and a resistor 108 is connected in the negative feedback circuit, the capacitance of the capacitor 107 and the resistor 10 are output from the output terminal 109 of the operational amplifier 106.
Generates a square wave with a constant frequency that is inversely proportional to the resistance value of 8. Transistor 110 only when the potential of terminal 109 is high
A collector current of a constant value flows through the capacitor 111, which detects changes in relative humidity as changes in capacitance, and charges and smoothes a capacitor 112.

On the one hand, a resistor 113 connected in parallel with a capacitor 112
Therefore, the potential of the terminal 114 becomes a potential proportional to the capacitance of the capacitor 111. That is, the potential of the terminal 114 is a potential expressed by a linear function with relative humidity as a variable.

Part B is a temperature signal output part, and the combined resistor 116 is a combined resistance including the resistor 116 that detects temperature change as a resistance change. This is the value. That is, the potential of the terminal 117 can be approximately expressed as a linear function of the resistance 116, that is, the temperature variable.

Part 0 is a multiplication part, which includes FET11s and operational amplifier 120.
It multiplies the input terminals of terminal 114 and terminal 117, amplifies it to a voltage according to the degree of increase determined by resistor 121 and FICTllG, and outputs it from terminal 122.

The D section is an adder section that connects the voltage at the terminal 122 and the power supply voltage to the resistor 12.
It consists of an operational amplifier 126 which is an adder of a constant voltage divided at a ratio of 3 and a resistor 124, and outputs a dew point temperature value as a voltage value from a terminal 126.

FIG. 4 shows a third embodiment of the present invention, in which reference numeral 206 is a composite resistor consisting of a resistor 207 that detects temperature changes as resistance changes.

The voltage value at terminal 208 is a value obtained by dividing the voltage between terminals 209 and 210 into the ratio of the resistance values of resistor 206 and resistor 211.
It is possible to express it as a linear function using the resistance 207, that is, the temperature, as a variable. The operational amplifier 212 is a common-mode amplifier, and when a voltage expressed as a linear function of temperature is input to the non-inverting input terminal, the amplifier 212 generates an amplifier that responds to the degree of amplification determined by a combined resistance consisting of a resistor 213 and a resistor 214 that detects a change in relative humidity as a change in resistance. A voltage is output to terminal 216.

If the value of the combined resistance is the resistance 214, that is, the resistance value expressed by a linear function of relative humidity, then the voltage at terminal 216 is the voltage value expressed by the product of a linear function of temperature and a linear number of relative humidity. Become.

The operational amplifier 21 is an in-phase adder, and the terminal 2 indicates the voltage value of the terminal 216 and the potential obtained by dividing the voltage between the terminals 209 and 210 into the ratio of the resistance values of the resistor 218 and the resistor 219.
20 is added, and the voltage is output to the terminal 221. That is, the voltage value of the terminal 221 is the voltage value of the dew point temperature value expressed by the sum of the product term of the linear function of temperature and the linear function of relative humidity and a constant.

This shows the third embodiment of the present invention, and in the same figure, 3 o
6 is a resistor 307 that detects a change in relative humidity as a change in resistance.
It is a composite resistance consisting of The voltage value of terminal 308 is terminal 3
A value obtained by dividing the voltage between 09 and 310 into the ratio of the resistance values of the resistor 306 and the resistor 311 can be expressed as a linear function using the resistance 307, that is, the relative humidity as a variable.

The operational amplifier 312 is a common mode amplifier, and when a voltage expressed as a linear function of relative humidity is input to the non-inverting input terminal, a resistor 313 and a resistor 31 that detects a temperature change as a resistance change are input.
A voltage corresponding to the degree of increase determined by the composite resistor 316 consisting of 4 and the constant voltage output section 316 is output to the terminal 317.

Here, it is possible to set the value of the combined resistance 316 to be the resistance value of the resistance 314, that is, a resistance value that can be expressed as a linear function of temperature.
Since it is not easy to make the constant term match the value of the arithmetic expression (e), the constant term can be easily made to match by inserting a constant voltage output section in series with the resistor. Therefore, the voltage value at the terminal 317 is a voltage expressed by the product of a linear function of temperature and a linear function of relative humidity. The operational amplifier 318 is an in-phase adder that adds the voltage value at the terminal 317 and the voltage value at the terminal 321, which indicates the potential obtained by dividing the voltage between the terminals 309 and 310 into the ratio of the resistance values of the resistors 319 and 320. , a voltage value of a dew point temperature value expressed by the sum of a product term of a linear function of temperature and a linear function of relative humidity and a constant term is outputted to the terminal 322.

Effects of the Invention As is clear from the embodiments, the dew point temperature output device of the present invention calculates the dew point temperature td from the relative humidity ψ and the dry bulb temperature t.
Since the calculation is performed using a simple formula: atψ+bt+c<p+d, the circuit configuration of the calculator can be made simpler than in the past, and the calculation speed can be increased, so that the dew point temperature can be output immediately. Furthermore, a, b, C
The constant 2d is set so that no error occurs between the true dew point temperature and the practical range, so there is no problem in the practical range.

By changing this constant, the measurable range can be arbitrarily set.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the configuration of the dew point temperature output device of the present invention, Fig. 2 is an electric circuit diagram of the temperature output device in an embodiment of the present invention, and Fig. 6 shows the relationship between dry bulb temperature and dew point temperature. Figure 7 is a diagram showing the relationship between relative humidity and coefficient m, Figure 8 is a diagram showing the relationship between relative humidity and coefficient m.
The figure is a diagram showing the relationship between relative humidity and coefficient n. 1... Humidity signal output section, 2... River/temperature signal output section, 3... Multiplier, 4... River... Output section. Name of agent: Patent attorney Toshio Nakao Haga 1st person
1 Figure 2 Figure 4 Figure 6

Claims (3)

[Claims] (1) A humidity sensor that converts the relative humidity ψ (%) into an electrical signal, a temperature sensor that converts the dry bulb temperature t (°C) into an electrical signal, and the signals of this temperature sensor and the humidity sensor as input, and the dew point The temperature td is calculated using the formula td=atψ+bt+cψ+d, and the constants a, b, c, and d are set within the predetermined temperature and humidity range, and the true dew point temperature tdo and the dew point temperature td from the calculation formula are | A dew point temperature output device equipped with a calculator selected so that td-tdo|<1°C. (2) The arithmetic unit converts the constants a, b, c, and d of the arithmetic expression td into q=
Let b/a, p=c/a, r=d-apq, and td=a(
The dew point temperature output device according to claim 1, which performs the calculation expressed as t+p)(ψ+q)+r. (3) The arithmetic unit converts relative humidity changes into voltage changes and has a relative humidity signal voltage output section that is expressed as a linear function with relative humidity as a variable, and a relative humidity signal voltage output section that converts temperature changes into resistance changes and is expressed as a linear function that uses temperature as a variable. 2. The dew point temperature output device according to claim 1, comprising a temperature signal output section that changes the degree of amplification by a resistance expressed by a function, and a multiplier that multiplies the temperature output signal and the relative humidity output signal.